Course Introduction：Field operation guide in MySQL: Add, modify, and delete fields. Add field: ALTER TABLE table_name ADD column_name data_type [NOT NULL] [DEFAULT default_value] [PRIMARY KEY] [AUTO_INCREMENT] Modify field: ALTER TABLE table_name MODIFY column_name data_type [NOT NULL] [DEFAULT default_value] [PRIMARY KEY]
2025-04-11 comment 0 446
Course Introduction：This article details MongoDB's Create, Read, Update, and Delete (CRUD) operations. It covers inserting, updating, deleting, and querying data using both the MongoDB shell and drivers, emphasizing efficient querying of large datasets and best practic
2025-03-04 comment 0 871
Course Introduction：Use the ALTERTABLE statement to modify the table structure, 1. Add columns: ALTERTABLEtable_nameADDcolumn_namedata_type[constraints]; 2. Delete columns: ALTERTABLEtable_nameDROPCOLUMNcolumn_name (the data will be deleted permanently); 3. Modify column data type: MODIFY for MySQL, ALTERCOLUMNTYPE for PostgreSQL/SQLServer/Oracle; 4. Rename columns: RENAMECOLUMN for MySQL and PostgreSQL, SQLSe
2025-08-07 comment 0 733
Course Introduction：MySQL supports CHECK constraints to force domain integrity, effective from version 8.0.16; 1. Add constraints when creating a table: Use CREATETABLE to define CHECK conditions, such as age ≥18, salary > 0, department limit values; 2. Modify the table to add constraints: Use ALTERTABLEADDCONSTRAINT to limit field values, such as name non-empty; 3. Use complex conditions: support multi-column logic and expressions, such as end date ≥start date and completion status must have an end date; 4. Delete constraints: use ALTERTABLEDROPCONSTRAINT to specify the name to delete; 5. Notes: MySQL8.0.16, InnoDB or MyISAM needs to be quoted
2025-08-06 comment 0 465
Course Introduction：Modifying XML content requires programming, because it requires accurate finding of the target nodes to add, delete, modify and check. The programming language has corresponding libraries to process XML and provides APIs to perform safe, efficient and controllable operations like operating databases.
2025-04-02 comment 0 1101
Course Elementary 13880
Course Introduction：Scala Tutorial Scala is a multi-paradigm programming language, designed to integrate various features of object-oriented programming and functional programming.
Course Elementary 82436
Course Introduction："CSS Online Manual" is the official CSS online reference manual. This CSS online development manual contains various CSS properties, definitions, usage methods, example operations, etc. It is an indispensable online query manual for WEB programming learners and developers! CSS: Cascading Style Sheets (English full name: Cascading Style Sheets) is an application used to express HTML (Standard Universal Markup Language).
Course Elementary 13230
Course Introduction：SVG is a markup language for vector graphics in HTML5. It maintains powerful drawing capabilities and at the same time has a very high-end interface to operate graphics by directly operating Dom nodes. This "SVG Tutorial" is intended to allow students to master the SVG language and some of its corresponding APIs, combined with the knowledge of 2D drawing, so that students can render and control complex graphics on the page.
Course Elementary 24687
Course Introduction：In the "AngularJS Chinese Reference Manual", AngularJS extends HTML with new attributes and expressions. AngularJS can build a single page application (SPAs: Single Page Applications). AngularJS is very easy to learn.
Course Elementary 27533
Course Introduction：Go is a new language, a concurrent, garbage-collected, fast-compiled language. It can compile a large Go program in a few seconds on a single computer. Go provides a model for software construction that makes dependency analysis easier and avoids most C-style include files and library headers. Go is a statically typed language, and its type system has no hierarchy. Therefore users do not need to spend time defining relationships between types, which feels more lightweight than typical object-oriented languages. Go is a completely garbage-collected language and provides basic support for concurrent execution and communication. By its design, Go is intended to provide a method for constructing system software on multi-core machines.
How to add delete button in PHP form to delete a row from MySQL table
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Does the teacher have complete authority to add, delete, modify, and check?
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Dear masters, how to write the PHP interface?
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